1. Field of the Invention
This invention relates to a scroll-type refrigerant fluid compressor, and more particularly, to a lubricating mechanism for lubricating the internal component parts of the scroll-type refrigerant fluid compressor.
2. Description of the Related Art
Scroll-type refrigerant fluid compressors are known in the prior art. For example, Japanese Utility Model Application Publication No. 59-142490 discloses a scroll-type refrigerant fluid compressor which will be described below with reference to FIG. 1. In the description, the right side of FIG. 1 is referred to as a rear or a rearward end, and the left side of FIG. 1 is referred to as a front or a forward end.
The scroll-type refrigerant fluid compressor comprises compressor housing 10. Compressor housing 10 comprises a cup-shaped casing 11 which is open at its forward end and closed at its rearward end. Compressor housing 10 further comprises a front end plate 12, which is disposed on cup-shaped casing 11 at its forward end to enclose an inner chamber 100 of cup-shaped casing 11. Front end plate 12 is secured to cup-shaped casing 11 by a plurality of peripherally disposed bolts 16. The mating surfaces between front end plate 12 and cup-shaped casing 11 are sealed by an O-ring 14. An inlet port 41 and an outlet port 51 are formed through a peripheral side wall 115 of cup-shaped casing 11, adjacent to a suction chamber 40 and a discharge chamber 50, respectively.
An opening 121 is centrally formed through front end plate 12. An annular plate member 15 is fixedly secured to a front end surface of front end plate 12 by a plurality of peripherally disposed bolts (not shown). A sleeve portion 151 forwardly projects from an inner periphery of annular plate member 15. Sleeve portion 151 is arranged, such that its longitudinal axis is aligned with the center of opening 121. A drive shaft 13 is disposed through an inner hollow space of sleeve portion 151, and through opening 121 of front end plate 12. A bearing 17 is peripherally disposed within the forward end of sleeve portion 151, and rotatably supports the forward end of drive shaft 13. At its opposite or inner end, drive shaft 13 includes a disk-shaped rotor 131, which rotates with drive shaft 13 and is integrally formed therewith. Rotor 131 is rotatably supported within opening 121 of front end plate 12 by a peripherally disposed bearing 18. A drive pin 132 projects rearwardly from the inner axial end surface of disk-shaped rotor 131 at a position offset from the longitudinal axis of drive shaft 13. When drive shaft 13 rotates, pin 132 orbits about the longitudinal axis of drive shaft 13. Power for rotating drive shaft 13 is transferred from an external power source (not shown) to drive shaft 13 via electromagnetic clutch 60, which is disposed about sleeve portion 151 of annular plate member 15 through a bearing 19.
A fixed scroll 20 is disposed within inner chamber 100 of cup-shaped casing 1 1, and is fixedly secured to the closed rear end portion of cup-shaped casing 11 by a plurality of bolts 111. Fixed scroll 20 comprises a circular end plate 21 and a spiral element or wrap 22, integrally formed therewith and extending axially from the forward end surface of circular end plate 21. Circular end plate 21 divides inner chamber 100 into suction chamber 40, located forward of circular end plate 21, and discharge chamber 50, located to the rear of circular end plate 21.
Circular end plate 21 comprises a circular groove 200 formed in the circumferential surface thereof. A seal ring 201 is disposed in groove 200 to seal the region between the peripheral surface of circular end plate 21 and the inner surface of peripheral side wall 115 of cup-shaped casing 11. This arrangement effectively isolates discharge chamber 50 from suction chamber 40. A hole or discharge port 21a is formed through circular end plate 21 at a central location, i e., at a position near the center of spiral element 22. Hole 21a links a central fluid pocket 400b (discussed below) to discharge chamber 50.
An orbiting scroll 30 is disposed in suction chamber 40 and comprises a circular end plate 31 and spiral element or wrap 32, integrally formed therewith and extending from the rear end surface of circular end plate 31. Spiral element 32 of orbiting scroll 30 interfits with spiral element 22 of fixed scroll 20 at an angular offset of 180.degree., and at a predetermined radial offset, to form at least one pair of sealed-off fluid pockets 400 therebetween.
A groove 221 is formed at an axial end surface of spiral element 22 of fixed scroll 20 substantially along the entire length thereof A seal element 22a is fittedly disposed in groove 221 along the entire length thereof Seal element 22a in groove 221 is sealingly in contact with the rear end surface of circular end plate 31 of orbiting scroll 30 during operation of the compressor. Similarly, a groove 321 is formed at an axial end surface of spiral element 32 of orbiting scroll 30 substantially along the entire length thereof. A seal element 32a is fittedly disposed in groove 321 along the entire length thereof Seal element 32a in groove 321 is sealingly in contact with the front end surface of circular end plate 21 of fixed scroll 20 during operation of the compressor.
A rotation preventing/thrust bearing device 70 is disposed within inner chamber 100 and prevents orbiting scroll 30 from rotating when drive shaft 13 rotates.
Orbiting scroll 30 further comprises an annular boss 33, which axially projects from the forward end surface of circular end plate 31 at a central location, opposite spiral element 32. A bushing 80 is disposed within a bearing 81 in a hollow space 331 defined by boss 33. Orbiting scroll 30 is supported on bushing 80 through boss 33 and bearing 81, such that bushing 80 may rotate with respect to orbiting scroll 30. An axial hole 82 is formed in bushing 80, at a position offset from the longitudinal axis of bushing 80. Drive pin 132, rearwardly projecting from the inner axial end surface of disk-shaped rotor 131, is fittedly and rotatably disposed in axial hole 82. Thus, orbiting scroll 30 is ultimately supported on drive pin 132 by bushing 80. When drive shaft 13 rotates, drive pin 132 orbits about the longitudinal axis of drive shaft 13. Bushing 80 both rotates with respect to its longitudinal axis, and orbits about the longitudinal axis of drive shaft 13, causing orbiting scroll 30 to undergo orbital motion with respect to the longitudinal axis of drive shaft 13. Although bushing 80 may rotate within boss 33, rotation of orbiting scroll 30 is prevented by rotation preventing mechanism 70.
In operation, rotation of drive shaft 13 causes a corresponding orbital motion of orbiting scroll 30 about the longitudinal axis of drive shaft 13. The plurality of line contacts formed between spiral elements 22 and 32 shift towards the center of the spiral elements. The plurality of pairs of fluid pockets 400 defined by the line contacts between spiral elements 22 and 32 follow each other toward the center of the spiral elements 22 and 32, and undergo a corresponding reduction in volume. A pair of fluid pockets 400 approach the center of spiral elements 22 and 32 and merge with each other to form a single, central fluid pocket 400b. Therefore, fluid or refrigerant gas introduced into suction chamber 40 from an external refrigerant circuit through inlet port 41 is taken into outer fluid pockets 400a, and is compressed inwardly towards the single central fluid pocket 400b of spiral elements 22 and 32. The compressed fluid in the single central fluid pocket 400b is discharged into discharge chamber 50 through hole 21a. The compressed fluid is further discharged to the external fluid circuit from discharge chamber 50 through outlet port 51.
In the scroll-type refrigerant fluid compressor described above, it is necessary to lubricate the frictional contacting surfaces between bushing 80 and bearing 81 and the internal frictional contacting surfaces of the bearing 81. In response to this requirement, a single, straight passageway 34 is formed in orbiting scroll 30 as a lubricating oil supply path. One end of passageway 34 is open to an outer side wall surface of an outer region of spiral element 32 of orbiting scroll 30, adjacent to the rear end surface of circular end plate 31 of orbiting scroll 30. The other end is open to an inner peripheral side surface of boss 33, adjacent to the front end surface of circular end plate 31 of orbiting scroll 30. Accordingly, passageway 34 is formed to link one of the outer sealed-off fluid pockets 400a with hollow space 331 of boss 33 in fluid communication during operation of the compressor. By passageway 34, the refrigerant gas and the mists of the lubricating oil suspended in the refrigerant gas in the outer sealed-off fluid pocket 400a are conducted into hollow space 331 of boss 33 by virtue of the pressure difference therebetween during operation of the compressor. The lubricating oil conducted into hollow space 331 of boss 33 flows through the small air gaps created between bushing 80 and bearing 81 and the interior of the bearing 81. Thus, the frictional contacting surfaces between bushing 80 and bearing 81 and the internal frictional contacting surfaces of the bearing 81 are lubricated.
Nevertheless, according to this known embodiment, passageway 34 must be inclined with respect to the longitudinal axis of circular end plate 31 of orbiting scroll 30. Therefore, a complicated manufacturing process is required when passageway 34 is formed through circular end plate 31 of orbiting scroll 30.
FIGS. 2 and 3 illustrate scroll type refrigerant fluid compressors in accordance with two other prior art embodiments. In FIGS. 2 and 3, the same reference numerals are used to denote identical elements of the compressor shown in FIG. 1. Consequently, further explanation thereof is omitted. Additionally, the right side of either FIG. 2 or 3 is referred to as a rear or a rearward end, and the left side of either FIG. 2 or 3 is referred to as a front or a forward end.
With reference to FIG. 2, a lubricating oil supply path 341 is formed in circular end plate 31 of orbiting scroll 30. Lubricating oil supply path 341 comprises a radial passageway 341a and a first and a second axial passageways 341b and 341c, which are formed perpendicular to radial passageway 341a. One end of radial passageway 341a is linked to one end of first axial passageway 341b, and the other end is open to an outer peripheral surface of circular end plate 31 of orbiting scroll 30. The other end of first axial passageway 341b is open to a central region of the front end surface of circular end plate 31 of orbiting scroll 30 within annular boss 33. One end of second axial passageway 341c is open to the rear end surface of circular end plate 31 of orbiting scroll 30, adjacent to an outer side wall surface of an outer region of spiral element 32 of orbiting scroll 30. The other end is linked to radial passageway 341a at a generally intermediate location thereof. A plug member 341d is plugged into the second end of radial passageway 341a, which is open to the outer peripheral surface of circular end plate 31 of orbiting scroll 30. As a result, lubricating oil supply path 341 links one of the outer sealed-off fluid pockets 400a with hollow space 331 of boss 33 in fluid communication during operation of the compressor.
However, in this known embodiment, when lubricating oil supply path 341 is fabricated, a process of separately forming three passageways 341a, 341b and 341c, and a subsequent process of plugging the plug member 341d into the second end of radial passageway 341a must be carried out. This results in a complicated manufacturing process of lubricating oil supply path 341.
With reference to FIG. 3, an axial passageway 342 is formed through a central region of circular end plate 31 of orbiting scroll 30 as a lubricating oil supply path. One end of axial passageway 342 is open to a central region of the rear end surface of circular end plate 31 of orbiting scroll 30. The other end is open to a central region of the front end surface of circular end plate 31 of orbiting scroll 30 within annular boss 33. As a result, axial passageway 342 links the single, central fluid pocket 400b with hollow space 331 of boss 33 in fluid communication during operation of the compressor.
An orifice tube 342a is fixedly disposed in axial passageway 342 so as to cause a throttling effect when the refrigerant gas flows therethrough from single, central fluid pocket 400b to hollow space 331 of boss 33 during operation of the compressor. Alternatively, axial passageway 342 may be formed as a very fine hole to have a throttling effect by itself.
In operation of the compressor illustrated in FIG. 3, the refrigerant gas and the mists of the lubricating oil suspended in the refrigerant gas in single, central fluid pocket 400b are conducted into hollow space 331 of boss 33 by virtue of the pressure difference therebetween. When the refrigerant gas flows through axial passageway 342 from single, central fluid pocket 400b to hollow space 331 of boss 33, the refrigerant gas turns from a gas under high pressure into a gas under low pressure by virtue of the throttling effect of axial passageway 342. The lubricating oil conducted into hollow space 331 of boss 33 flows through the small air gaps created between bushing 80 and bearing 81 and the interior of the bearing 81. Thus, the frictional contacting surfaces between bushing 80 and bearing 81 and the internal frictional contacting surfaces of bearing 81 are lubricated.
However, in this known embodiment, a high level of skill is required to either carry out a process of fixedly disposing orifice tube 342a within axial passageway 342 or to form axial passageway 342 as a very fine hole through circular end plate 31 of orbiting scroll 30.